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A321800
Delete the decimal digits of n that appear exactly once; write -1 if all digits disappear.
4
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 22, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 33, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 44, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 55, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 66, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 77, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 88, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 99, 0, 11, -1, -1, -1, -1, -1, -1, -1, -1, 11, 111, 11, 11, 11, 11, 11, 11, 11, 11, -1, 11, 22, -1, -1, -1, -1, -1, -1, -1, -1, 11, -1, 33, -1, -1, -1, -1, -1, -1, -1, 11, -1, -1, 44, -1, -1, -1, -1, -1, -1, 11, -1, -1, -1, 55, -1, -1, -1, -1, -1, 11, -1, -1, -1, -1, 66, -1, -1, -1, -1, 11, -1, -1, -1, -1, -1, 77, -1, -1, -1, 11, -1, -1, -1, -1, -1, -1, 88, -1, -1, 11, -1, -1, -1, -1, -1, -1, -1, 99
OFFSET
0,12
COMMENTS
A companion sequence to A320485.
Digits that appear exactly once in n are erased. Leading zeros are erased unless the result is 0. If all digits are erased, we write -1 for the result (A321797 is another version, which uses 0 for the empty string).
More than the usual number of terms are shown in order to reach some interesting examples.
EXAMPLE
12321 becomes 1221, 1123 becomes 11, 11231 becomes 111, and 100223 becomes 22 (as we don't accept leading zeros). Note that 12345 disappears immediately and we get -1.
PROG
(Python)
def A321800(n):
return (lambda x: int(x) if x != '' else -1)(''.join(d if str(n).count(d) != 1 else '' for d in str(n)))
CROSSREFS
Sequence in context: A109014 A268357 A321804 * A130837 A010194 A280443
KEYWORD
sign,base,look
AUTHOR
Chai Wah Wu, Nov 19 2018
STATUS
approved